Feeder for pulverulent fuel.



E. C. COVERT.

' FEEDER FOR PULVERULENT FUEL.

APPLICATION FILED OCT. 28, 1915.

1 a 1 97,?99; lam-m1 Sept. 12. 1916.

W'iYNESSES verulent or finely divided fuel, such as coal.

lack of uniformity of feed, and a tendency UNITED STATES PATENT OFFICE.

EDSON C. COVERT, OF NEW KENSTNGTON, PENNSYLVANIA, ASSIGNOR TO HEYL &

PATTERSON, INC., OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENN-SYLVANIA.

Specification of Letters Patent.

Patented Sept. 12, 1916.

Application filed October 28, 1915. Serial No. 58,413.

of New Kensington, in the county of Vestmoreland and State ofPennsylvania, have invented a new and useful Improvement in Feeders forPulverulent Fuel; and I do hereby declare the following to be'a full,clear, and exact description thereof.

My invention relates to a feeder for pul- The most efficient feeder forpulverized coal is one that is always under perfect control, and forthis reason devices of this character have come to be known ascontrollers. The difficulties most commonly encountered in the use ofthese controllers are,

of the coal to continue to flow after the controller has stopped. Thistendency to flow, which is sometimes called flooding, is due to the verysmall angle of repose of dry pulverized coal, and this is accentuated,the drier and morefinely pulv :ized the coal. Nearly all the mechanicalcontrollers of this character employ some form of screw as a means offeeding, but on account of flooding the amount delivered to the burneris subject to considerable fluctuation and the stoppage of the flow ofcoal when the screw stops is by no means assured. Furthermore, where airis used for feeding the coal from the controller to the burner, theamount of pressure has considerable influence on the quantity of coalthat is delivered.

The object of my invention is to provide a controller or feeder of suchcharacter that the coal will be delivered in practically uniformquantities, and one which when the feeder is at rest, shuts off thesupply of coal completely and prevents flooding heretofore referred to.v

To these ends, my invention consists, generally stated, in combining twoscrew-feeders in such a way that neither can feed independently of theother and that when at rest, each seals the other against the passage ofany material. This is accomplished by mounting two screws of similarsize and pitch and of the same hand with their axes at such an angle toeach other that a line on the surface of one thread of one screw is inapproximate contact with a line on the surface of the space on the otherscrew; This line of Contact being common to both screws, it is evidentthat the thread of one screw effectually fills the space of the other.Thus the free flow of material along either screw is prevented.

In the accompanying drawings, Figure 1 is a plan view partly brokenaway, of my improyed feeder or controller; Fig. 2 is a side view partlybroken away; and Fig. 3 is a section on the line 3-3, Fig. 1.

In the drawing, the numeral 2 designates a suitable housing or casinghaving the material-receiving chamber 3, the discharge opening 4, andtwo cylindrical intersecting passages 5 connecting the receiving-chamberwith the discharge opening. The inter secting passages communicateattheir point of intersection as at 5. Mounted in the passages 5 arethe'feed-screws 6 and 7, said feed-screws engaging where said passagesintersect, and being. arranged with their axes at such an angle to eachother that a line on the surface of one thread of one screw isinapproximate contact with a line on the surface of one space of the otherscrew. This line of contact being common to both screws, it is evidentthat the thread of one screw effectually fills the space of the other,and thus the free flow of ma-' terial along either screw is prevented.The screws are provided with the pinions 8 driven by the intermediatepinion 9, so that the screws rotate in the same direction. As

both screws are restrained from endwise cept against the movement ofmaterial at a faster rate of travel than would be produced by therotation of the screws. There is thus obtained a uniform feedproportionate to the rate of movement of the screws and absolutestopping of the feed while the screws are at rest. In this manner,fioodingis prevented, and the uniformity of feed is obtained by reasonof the fact that there is no flow of fuel except as it is advanced bythe screws, and when the screws. stop, the flow of fuel absolutelyceases.

What I claim is: v 1. In a feeder or controllerrfor pulverulent fuel,the combination with a suitable casing, an inlet opening, a dischargeopening, two feed screws located in said housing adapted to rotate inthe same direction and having their threads in'engagement throughout aportion only of the length of the screws to seal the discharge opening.

2. In a feeder or controller for pulveru lent fuel,-the combinationof asuitable casing, having an inlet and discharge opening;

" two screws located in said casing with their axes at an angle to eachotheradapted to rotate in the same direction, and having threads inengagement with each other.

3. In a feeder or controller for pulverulent fuel, the combination of asuitable casing, having an inlet and discharge opening;

two screws located in said casing with their fuel delivery passages, twoconveyer screws located in said passages with their axes at an angle toeach other, and their threads in full engagement at a point in saidpassages.

5. In a feeder or controller for pulverulent fuel, the combination of. asuitable casing, having inlet and outlet openings, a con-'- veyerchamber having two fuel delivery passages connecting the inlet anddischarge and crossing each other, said passages communicating at thepoint of intersection, two conveyer screws in said passages having theirthreads engaging at the point of intersection of said passages, andmeans for driving said screws in the same direction.

6. In a feeder or controller for pulveru lent fuel, the combination of asuitable casing, having inlet and discharge openings, a conveyer chamberinterposed between said inlet and discharge and provided with twodelivery passages at an angle to each other and intersecting at a pointintermediate said inletand discharge, two conveyer screws in saidpassages with their screws in engagement at the intersection of saidpassages, and means for rotating said screws in the same direction.

7. In a feeder or controller for pulverulent fuel, the combination of asuitable casing, having inlet and discharge openings, 31 and a conveyerchamber interposed between said openings, said conveyer chamber havingintersecting conveyer passages com- I municating with the said inlet anddischarge openings, and conveyer screws in said passages with screws oflike hand and in engagement with each other at the intersecting point ofthe screws at the intersection of said passages.

In testimony whereof, I, the said EDSON C. COVERT, have hereunto set myhand.

, EDSON C. COVERT. Witnesses: v

JOHN F. WILL, J. R. KELLER.

